Note : Make sure you have included these file for working drag and drop functionality:

<!-- Have to must add without this css drag and drop will not work -->
<!-- Make sure you have given correct path for href attribute -->
<link type="text/css" href="Styles/jquery-ui-1.8.24.custom.css" rel="Stylesheet" />
<!-- Have to must add without this drag and drop will not work →
<!-- Make sure you have given correct path for src attribute -->
<script type="text/javascript" src="Scripts/jquery-1.8.2.min.js"></script>
<script type="text/javascript" src="Scripts/jquery-ui-1.8.24.custom.min.js"></script>

Jquery Error: Draggable function is not defined or not found. Droppable function is not found or not defined.This error occur when you might forget to add jquery-ui-1.8.24.custom.css file

<!-- Have to must add without this css drag and drop will not work -->
<!-- Make sure you have given correct path for href attribute -->
<link type="text/css" href="Styles/jquery-ui-1.8.24.custom.css" rel="Stylesheet" />

or might forget to add jquery-1.8.2.min.js or jquery-ui-1.8.24.custom.min.js file then in this case generally we get this error.

<!-- Have to must add without this drag and drop will not work →
<!-- Make sure you have given correct path for src attribute -->
<script type="text/javascript" src="Scripts/jquery-1.8.2.min.js"></script>
<script type="text/javascript" src="Scripts/jquery-ui-1.8.24.custom.min.js"></script>